Assessing the performance of RIS-assisted integrated satellite-UAV-terrestrial networks

Abstract

This project investigated the secrecy performance of Reconfigurable Intelligent Surface (RIS) integrated satellite unmanned aerial vehicle (UAV) relay networks under the threat of eavesdropping and co-channel interference in a downlink scenario. The satellite acted as the primary signal source, while the UAV relayed the legitimate signal to the destination user through the RIS, which ensured a virtual line-of-sight transmission. The destination user was the intended recipient of the signal, whereas the eavesdropper intercepted the signal directly from the satellite. Both the user and the eavesdropper were subjected to co-channel interference. To assess the impact of this interference on secrecy performance, closed-form expressions for the secrecy outage probability (SOP) were derived with and without co-channel interference. This involved analyzing the received signals at the relay, destination, and eavesdropper links to determine their respective Signal-to-Noise Ratios (SNRs). From these analyses, the probability density functions (PDFs) and cumulative distribution functions (CDFs) necessary to calculate the SOP were derived. The derived expressions were plotted using MATLAB, and various channel parameters were varied to evaluate their effects on network performance. The findings indicated that an increase in the power of co-channel interferers at the eavesdropper, coupled with an increase in their number, led to a lower SOP, thereby improving secrecy performance as the eavesdropper received a weaker and distorted signal. Additionally, an increase in the eavesdropper’s SNR resulted in a higher SOP, further degrading secrecy performance due to enhanced signal reception by the eavesdropper. The study concluded by recommending the inclusion of more legitimate users in the network and a comprehensive analysis of a dual-link network that encompassed both uplink and downlink communication to improve security measures.